Myxoviridae
Influenza viruses belong to a broad family of RNA viruses, the Orthomyxoviridae (myxo=mucus) viruses. Orthomyxoviridae viruses as well as the closely related family or RNA viruses, Paramyxoviridae viruses, are characterized by a negative-stranded RNA genome (segmented or non-segmented, respectively), having, an inner ribonucleoprotein (RNP) core surrounded by a lipid bilayer membrane from which spikes protrude. The spikes are of three kinds: a hemagglutinin (HA) which agglutinates erythrocytes, an enzyme neuraminidase (NA) which releases the virus from cells and a small number of copies of the M2 protein that serves as an ion channel. These spikes in influenza (in Parmyxoviridae virus these are HN and F) are involved in hemagglutination, hemolysis of erythrocytes etc. and cleavage of the receptor (on the cell) anti-receptor (on the virus) bond, and reflect the ability of the virus to enter the nucleoprotein core into cells.
Influenza is a highly communicable acute respiratory disease that predisposes to a number of complications, resulting in a severe world-wide economic burden. Prevention and control of both the annual influenza epidemics and its infrequent but severe pandemic outbreaks are hitherto achieved by the use of vaccines and newly emerging antiviral drugs.
Unfortunately, the vaccines provide sometimes lower than desirable protection, particularly in the immuno-compromised and the elderly, the two most susceptible subpopulations (Keren. G., et al. J. Med. Virol. 25:85-89 (1988); Admon, D., et al. Vaccine 15:1518-1522 (1997)). Furthermore, the vaccines currently available are designated for intramuscular injection, resulting mainly in serum antibodies.
As to antiviral drugs, two classes of antiviral drugs are used:
(i) Anti-M2 inhibitors amantadine and rimantadine, effective against A strains only (World Health Organization, WHO Org. Rep. Ser., Geneva. 642:1-63 (1980)). A reduction in the severity and duration of the signs and symptoms is recorded when they are administered within 48 hrs of disease onset (Centers for Disease Control and Prevention, 1996. Prevention and control of influenza: Recommendation of the advisory committee on immunization practices (ACIP). MMWR45(RR-5), 1-24);
(ii) Neuraminadase inhibitors, effective against both A and B viruses. As prophylactics, these inhibitors are 70-90% effective and may shorten the duration of illness by 1.5 days when used within the first 48 hr (Treanor, J., Falsey, A., Antiviral Res. 44:79-102 (1999)).
Vaccinium Genus
Vaccinium is a genus of evergreen or deciduous berry-bearing ericaceous shrubs including the various kinds of blueberries and the true cranberries.
Physicians have long recommended consumption of cranberry juice to avoid urinary tract infections. It was hypothesized that the prevention of bacterial infections is due to the inhibition of E. coli adhesion to uroepithelial cells by cranberry constituents (Ofek et al., 1991, ibid.). Studies have shown that cranberries contain high and low molecular weight constituents [nondialyzable material (NDM) and proanthocyanidins, respectively], which act in vitro to inhibit the adhesion of diverse microbial species (Ahuja et al., 1998 ibid.; Burger et al., 2000, ibid.; Foo et al., 2000a, ibid.; Weiss et al., 1998 ibid.; Zafriri et al., 1998, ibid). It has been suggested that cranberry proanthocyanidins are one of the active anti-adhesion agents (Foo et al., 2000a, ibid.).